MILWAUKEE — Jon Niese was Mr. Dependability before hitting the disabled list earlier this month, but he still has cobwebs to shake since his return.

Not that this Mets lineup gave him much room for error Saturday night.

With Niese shaky during a key fifth inning and the big hit nowhere to be found, the Mets fell 5-2 to the Brewers in front of 39,292 at Miller Park.

Niese later expressed unhappiness he was yanked for a pinch-hitter in the sixth inning.

After Niese allowed three runs in the fifth to put the Mets in a 3-2 hole, manager Terry Collins sent up Eric Campbell in the sixth to pinch hit for the pitcher, who was batting eighth. Campbell struck out.

If Niese had been batting ninth, his turn might not have come until the seventh inning.

“I thought I should have been out there anyway, despite whether I was up eighth or not,” Niese said. “But Terry makes those decisions. Those are out of my control. I could have gone one or two more [innings].”

But Collins wanted a better opportunity to tie the game after watching Niese allow those three runs with two outs in the fifth.

“He certainly deserved to go back out, but we’ve been having a tough time scoring, so I thought we had to hit in the sixth,” Collins said.

The loss left the Mets (49-55) needing a victory in Sunday’s series finale to reach .500 for the 10-game road trip. That might be an obtainable goal with phenom Jacob deGrom set to pitch, but it also isn’t the kind of result the Mets had hoped for after winning eight of their last 10 games before the All-Star break.

Niese (5-6) allowed three earned runs on five hits with two walks and four strikeouts. The lefty also scuffled at Seattle in his return from the disabled list on Monday, when he surrendered four earned runs over six innings. The performance against the Mariners snapped Niese’s streak of 21 straight starts in which he had allowed three earned runs or fewer.

On Saturday, Jonathan Lucroy’s shot off the center-field fence for an RBI double tied it in the fifth before Ryan Braun put the Brewers ahead with a run-scoring single.

Earlier in the inning, Niese had unloaded a wild pitch that allowed Jean Segura to score from third with two outs for the first run.

“We had 0-2 with a runner at third base, we should get out of that inning,” Collins said. “Five two-out runs doesn’t help us.”

Niese appeared frustrated when the inning’s leadoff hitter, Mark Reynolds, blooped a single to center. Chris Young didn’t get much of a jump on the ball, which landed in front of him.

“I gave up three runs, which caused me to cut my game short,” Niese said. “They just started attacking me earlier there, and I made some mistakes and paid for them again.“Them getting those runs with two outs was frustrating. They hit it where we weren’t, and just very frustrating.”

Reynolds connected for a solo homer in the sixth against Carlos Torres to extend the Brewers’ lead to 4-2 and Khris Davis’ RBI single in the eighth added another.

Young doubled in the sixth and eighth innings, but on both occasions was left stranded. In the eighth, Wilmer Flores was caught looking at strike three from lefty Will Smith.

Curtis Granderson slapped a full-count pitch just inside the right-field foul pole in the fifth for a solo homer that gave the Mets a 2-0 lead. Lucas Duda’s RBI single in the third gave the Mets their first run.

“When you’re up 2-0 and you’ve got Jon Niese as well as he was, you kind of like your chances in the situation,” Collins said. “I don’t know what happened, but we had a chance to get out of [the fifth] and we didn’t.”